When compressing air or other semi-saturated compressible fluids, it is necessary to remove therefrom as much moisture as possible to avoid over-stressing and damaging the positive displacement pistons of the compressor. Most such equipment operates on an unattended basis, and therefore an automatic and very reliable system must be provided to monitor the liquid condensate level in the gas scrubber to maintain a safe liquid level therein, to avoid overflow of liquid into the compressor cylinders. The present invention has for its major objective to fulfill this need in a practical, reliable and economical manner.
U.S. Pat. No. 3,970,099 discloses a liquid level responsive vent valve for the general purposes of the present invention and this patented vent valve, together with an improvement thereof, is utilized in the present invention. More particularly, in the present invention, a very sensitive small pneumatic signal responsive diaphragm spool valve is utilized in parallel relationship with the float operated vent valve of the prior patent, so that when the latter is opened due to rising of the liquid level in the scrubber a small pneumatic control signal is delivered through the spool valve to a pneumatic control chamber on one side of a relatively large diaphragm of an automatic dump valve mounted on the side wall of the scrubber and having an inlet located deeply in the scrubber, to avoid the possibility of freeze-up. The small pneumatic signal sent through the spool valve to the large diaphragm chamber of the dump valve opens the latter and drains condensate from the scrubber to automatically maintain its liquid level within prescribed safe limits.
Another object of the invention is to provide a liquid dump valve of the above type which can be quickly manually operated whenever necessary or desirable.
Other objects and advantages of the invention will become apparent to those skilled in the art during the course of the following detailed description .